1. Field of the Invention
The present invention relates to a developer cartridge for a wet-type image forming apparatus. More particularly, the present invention relates to a developer cartridge with a filter to prevent toner sludge from being supplied to an image forming apparatus.
2. Description of the Related Art
Image forming apparatuses are typically classified as either monochrome image forming apparatuses or color image forming apparatuses. A monochrome image forming apparatus forms a monochrome image using a single color developer, while a color image forming apparatus forms a color image using different color developers, typically, magenta, cyan, yellow and black.
As widely known to those skilled in the relevant art, an electrophotographic image forming apparatus forms an electrostatic latent image on an organic photoconductor (OPC), which is charged with a predetermined electric potential by a charging unit, by scanning the OPC with laser beams projected from a laser scanning unit. The electrostatic latent image is developed into a visible image with developer, and the visible image is transferred to paper. In a color image forming apparatus, electrostatic latent images formed on respective color OPCs are developed into visible color images with color developers, and the separate color images are transferred and superimposed onto an intermediate transferring medium such as an intermediate transfer belt (ITB). The superimposed color images are then transferred from the intermediate transferring medium to a paper. The color images are fused onto the paper through a fusing process, and the paper is discharged from the image forming apparatus.
FIG. 1 shows a conventional color image forming apparatus which performs two transferring steps using an intermediate transfer belt (ITB). Referring to FIG. 1, the color image forming apparatus comprises an ITB 10, a support roller 11, T1 rollers 12, 13, 14, 15 which are provided by n color, organic photoconductor (OPCS) 16, 17, 18, 19 which are also provided by color, a T2 roller 20, and a belt drive roller 21.
Black (K), cyan (C), magenta (M) and yellow (Y) developers are attracted to electrostatic latent images formed on the respective OPCs 16, 17, 18, 19 through developing processes. The T1 rollers 12, 13, 14, 15 correspond to the OPCs 16, 17, 18, 19 and the ITB 10 is located between the rollers 12, 13, 14, 15 and the OPCs 16, 17, 18, 19. Accordingly, the developers attracted to surfaces of the respective OPCs 16, 17, 18, 19 are transferred and overlaid onto a surface of the ITB 10 at a first transferring step of the T1 rollers 12, 13, 14, 15. Thus, a single complete color image is formed on the ITB 10 through the first transferring step. Next, the color image is transferred from the ITB 10 to a printing medium 23 at a second transferring step which is performed between the T2 roller 20 and the belt drive roller 21.
Developing units 26, 27, 28, 29 are provided by color to develop the images on the respective OPCs 16, 17, 18, 19 with color developers. The respective color developing units 26, 27, 28, 29 are supplied with developers from respective color developer cartridges 36, 37, 38, 39 through pumps P. Used developers, including a liquid carrier, which remain in the developing units 26, 27, 28, 29, are recovered to the developer cartridges 36, 37, 38, 39.
According to the above-described construction, the respective color developer cartridges 36, 37, 38, 39 are connected to the respective developing units 26, 27, 28, 29 when being mounted in a body of the image forming apparatus, and thereby supply the developers to the developing units 26, 27, 28, 29. The color developer cartridges 36, 37, 38, 39 are disposable so that each developer cartridge is replaced with a new one after the developer in the cartridge is consumed.
The developer contained in each developer cartridge 36, 37, 38, 39 is an ink which is a mixture of powder color toners and a liquid carrier in a predetermined ratio. With this type of developer, toner sludge or toner mass may remain in the developer cartridges 36, 37, 38, 39 when the image forming apparatus is used. If toner sludge or toner mass is supplied to the developing units 26, 27, 28, 29, the images do not develop normally and thus the image quality deteriorates.
This becomes more problematic if toner sludge or toner mass clogs a supply pipe for the developers. In this case, liquid toner cannot be supplied and thus printing is not performed.
Accordingly, there is a need for an improved apparatus for handling liquid toner in a wet type image forming apparatus.